King William Street station was the northbound terminus
of the City & South London railway -
the world's first electric underground railway. Originally designed
to be cable hauled, the line
proved popular and the original terminii (Stockwell at its southern
end) were too small to
cope with the resultant passenger numbers.

Extension northwards to Bank, Moorgate was also impossible
as the King William Street terminus
was facing east (the locomotives also had difficulty negotiating
its sharp curves and steep gradients),
so it was abandoned - a new line was built from just north of
Borough station (this one in a straight line),
running underneath the old one as far as London Bridge where a
new station was added.

The old tunnel can be seen branching off just after
leaving Borough station
from the left hand side of a northbound train.

The section of the tunnels between Borough and the
London Bridge station area are relatively straight.

Though walking between the two, it seems a shorter distance
than if walked on the road at ground level.

The quality of construction of this section of the
line was poor - an indication can be seen here; the uncertain
level of the left hand side of the tunnel. The tunnels here are
of only 10' 2" diameter - after closure of this branch, the entire city branch of the
Northern Line was closed for enlargement.

The brick bulkhead seen in the photo is one of several
built in 1968/69 as part of ventilation works for London Bridge
Northern Line station platforms.

The point where the tunnels are directly above the
Northern Line platforms at London Bridge. The oblong holes in
the floor, guarded by the safety rails, provide ventilation windows
from the Northern Line platforms below. Looking up on the northbound
platform at London Bridge, these shafts are still visible and
provide a tantalizing glimpse of the old King William St tunnel
above.

The original southbound tunnel was obliterated here
at London Bridge when the station was redeveloped for the Jubilee
Line extension (Photo: Apr 2006). The northbound tunnel is still
intact, according to Richard Griffin.

The staircase and shaft that leads down to London
Bridge station. This emerges in the passageway leading from the
Northern Line escalators to the Northern Line platforms.

The station and tunnels are, in parts, more a wartime
time-capsule than that of an abandoned railway.

The stalactites increase closer to the river...

...as do the curves.

This shaft is intriguing - tunnelling was not allowed
directly beneath buildings so the tunnels had to follow the path
of roads on the surface. This caused some very sharp curves to
be built (the existing Piccadilly line between South Kensington
station and the old Brompton Road station is an example of this).
Where the road was narrow, the tunnels would have to be built
one of top of the other, as was the case with this line where
it passes under Swan Lane. This is the construction shaft built
at Old Swan Pier, from where tunnelling for the line started.

The shaft is 82 feet deep. The last 9 feet provided
a drainage sump. The southbound tunnel pictured here looking
north, is directly below the northbound tunnel, which is where
the ladder leads to.